Borussia Dortmund defender Lukasz Piszczek faces an uncertain amount of time on the sidelines after picking up a knee injury while on international duty.

The 32-year-old damaged ligaments in his right knee during Poland's 4-2 win over Montenegro in a World Cup qualifier which punched their ticket to Russia next summer. He picked up the injury during an unfortunate clash with his team-mate Wojciech Szczesny just prior to half-time.

Although he tried to continue, Dortmund's number 26 was unable to return for the second half and a later scan revealed the extent of the damage, although it is not yet clear for how long he will be sidelined.

Piszczek has been an ever-present for the Bundesliga-leading Westphalians this season and his loss will be a major blow to coach Peter Bosz.